Circuits employing germanium diodes as active elements



.w. A. MILLER 2,581,273

ODES AS ACTIVE ELEMENTS Jan. 1, 1952 CIRCUITS EMPLOYING GERMANIUM DIFiled Dec. 6, 1947 R E L I I H T M N R A N. l M A I Mm 3. When diode DIconducts, the voltage at terminal A goes relatively more positive (DIresistance decreases). The condenser Cl couples the resulting positivepulse to the terminal M which is the high potential side of resistorR22, thus preventing diode D2 from conducting .until condenser Cldischarges through its discharge path which includes. elements Di and RHon one side of terminal A and resistor RI on the other side of terminalA. When the condenser Cl discharges to avalue which permits terminal Mto go sufficiently' 'negative toallow diode D2 to conduct, this andcause terminal B to go more positive, as a result of which theresistance of diode DI is increased to a high value and ceasesconducting. This occurs because the raising of the positive potential onterminal B causes a positive pulse to in the system of Fig.

diode D2 will conductin one branch with the noncorresponding side of thediode in the other branch, and another capacitor coupling the othersides of the diodes in said branches.

3. A multivibrator system comprising two circuit branches arranged inelectrically parallel relationship,;- each circuit, branch including apair oi impedances capable of passing directcurrent and a two-elementdevice located between and in series with said impedances, said devicesbeing capable of exhibiting negative resistance characteristics, asource ofuni-directional potential connected across said circuitbranches, said devices being similarly arranged relative to said source,a pair of condensers cross-coupling opposite terminals of said devices,said source being so coupled to said devices and having such a valuethat both devices exhibit negative resistance characbe applied throughcondenser C2 to terminal N,

thus making terminal N. .go more positive, This cycle ofoperationsrepeats-itself at a rate determined by the values of condensers Cl andC2 and the resistance of the discharge path of the condensers. r i V Thevalue ofbattery E is determined by the fact that the diodes must swingfrom the right of point X to the neighborhoodoi X for the highresistance (ficut-oiiff),condition and considerably to the right ofpoint Xior the low resistance (fn) .conditionoithe diodes, I I ,Outputfrom the multivibrator may be taken from any one of points A, B, M or Nor any two of these points, provided that the output circuit into whichthe multivibrator works hasa high impedance in order not to interferewith the charge-discharge cycle of condensers Cl and C2. The output is awave which is approximately square at the low frequencies of 1 to 3.cycles per second. i i

\ In one embodiment oi the multivibrator of Fig. 3 successfully triedout, resistors-Rt, R2, RH and R22 were equal in value and each 1000ohms. With fixed values of R1, R1 I, R2 and R22, and by varyingthevalues of Cl and C2, the multivibrator .operated ;to produceoscillations at frequencies from 1 to 5000 cyclesper second.

Whatis claimed is: p V

1,. A multivibrator co pris n two circuit branchesarranged'electricallyin parallel, each branch including in the order named, a resistor, agermanium diode and another resistor, a source of unidirectionalpotential connected across said circuit branches, the diodes of saidbranches being similarly arranged relative to said source, and a pair ofcondensers cross-coupling the terminals of said germanium diodes, saidsource being so coupled to said diodes and having such a value that bothdiodes exhibit negative resistance characteristics and operate in thenegative resistance region of their characteristic curves.

2. A multivibrator system comprising two circuit branches arrangedelectrically in parallel relation, each circuit branch including a pairof impedances capable of passing direct current and a germanium diodelocated between and in series with said impedances, a source ofunidirectional potential having its positive terminal connected to thoseends of both branches which are connected to the germanium layer side ofthe diodes, and its negative terminal connected to the other ends ofsaid branches, the value of said source being such that both diodesexhibit negative resistance characteristics and operate in the negativeresistance regions of their characteristic curves. a capacitor couplingone side of the diode a of passing direct current,

teristics and operate as amplifiers in the negative resistance regionsof their characteristic curves.

4. A multivibrator circuit arrangement including a series circuitcomprising an impedance element capable of passing direct current, atwoterminal uni-directional nonlinear impedance device and a furtherimpedance, element capable means to apply direct operating potentialacross said series circuitfoi value at which said two-terminal deviceexhibits a negative resistance characteristic, the positive pole of saidtwo-terminal impedaiice device having operating potential thereonnegative with re spect to 'that'applied to the negative 'poleof saidtwo-terminal impedance device, another series circuit substantially thesame asand connected in parallel with the first said series circuit, andfurther impedance,devicescapable of passing al-v ternating currentcross-connecting unlike poles of the two-terminal. impedance devices 'ofsaid series circuits; V f

5. A multivibrator circuit arrangement including a series circuitcomprising animpedance element capable of passing directcurrent, a ger:manium diode and a further impedance element capable'of passing directcurrent, means r apply directoperating potential across said seriescircult of value at which said diode exhibits a negative resistancecharacteristic, the positive pole of saidvdiode having operatingpotential therecn negative with respect to that applied to the negativepole of said diode, another series circuit substantially the same as andconnected in parallel with the first saidseries circuit, and further i mpedance devices capable ofjpassing, alternating current cross-connectingunlike poles of the diodes of said series circuits. r A wave translatingcircuit arrangement', ineluding a series circuit'comprising an impedanceelement capable of passing direct'current, a two'- terminaluni-directional nonlf'near impedance device and a further impedanceelementcapable oipassing direct current, means. to apply dir'ectoperating potential across said series circuit of value at whichsaid'two- 'erminal deviceexhibit's a negative resistance characteristic, thepositive pole of saidtwo-terminal impedance device'having operatingpotential thereon negative withrespect to that applied to the negativepole oi said two-terminal impedance device, a further series circuitcomprising a unilateral impedance device and at least one impedanceelement capable ioi passing direct current connected across the firstsaid series circuit, the polarity of said unilateral impedance devicebeing arranged in operative relationship to the polarity .of potentialapplied-to e-fi a d e i r it snemri rim nc 6 devices capable of passingalternating current UNITED STATES PATENTS cross coupling said unilateraland said two-ter- Number Name Date minal unidirectional nonlinearimpedance de- 1,792,731 Thilo 17, 1931 vices. 2,152,016 Baesecke et a1Mar. 28, 1939 WILLIAM MILLER- 5 2,219,189 Lundstrom Oct. 22,19402,310,328 Swift Feb. 9, 1943 REFERENCES CITED 2,360,233 Hussey Oct. 10.1944 The following references are of record in the OTHER REFERENCES fileof this patent; 10 Article in Electronics, February 1946. entitledGermanium Crystal Diodes," pages 118 through 123.

